Clearance adjustment method of precision cylindrical roller bearing
Cylindrical roller bearings with tapered bores can obtain positive clearance, zero clearance or preload (as shown in Table 8) after installation, and can be accurate to ±1μm using envelope circle measuring equipment. In the following example, the installation of cylindrical roller bearings with a tapered inner bore (N10 and NN30) with a removable outer ring and the MGA 31 enveloping circle gauge will be introduced. The enveloping circle gauge is used to accurately set the radial clearance or preload of cylindrical roller bearings. Use a conventional inner diameter gauge to measure the raceway diameter of the outer ring (Figure 9). The measured diameter is transferred to the two hardened and fine ground surfaces of the enveloping circle gauge (Figure 10). Next, install the inner ring/roller assembly on the tapered shaft, and then place the enveloping circle gauge on the assembly (Figure 11). Move the bearing axially on the shaft until the enveloping circle gauge shows the required radial clearance or negative clearance value. Then, measure the distance from the inner ring to the shaft shoulder at 4 measuring points separated by 9 on the circumference with a gauge block (Figure 12). Remove the inner ring of the bearing, grind the spacer ring according to the distance value determined above, and install it on the shaft. Finally, install the bearing inner ring again and lock it with a nut. If there is no such measuring device, the clearance can be adjusted more accurately by measuring the raising distance from the inner ring to the end face of the taper shaft (taper 1:12). Installation clearance/preload limit speed single row cylindrical roller bearings 5 u200bu200b... 0 [μm] 0.75 · n* Grease lubrication 0 [μm] (zero clearance)) 0.75 ... 1.0 · n* Grease lubrication 0. .. 5 [μm] 1 ... 1.1 · n* Grease lubrication 0 ... 5 [μm] 1.0 · n* Oil-lubricated double row cylindrical roller bearings 5 u200bu200b... 0 [μm] 0.50 · n* Grease Lubrication 2 · 10 5 ·dm [mm] 0.50 ... 0.75 · n* Grease lubrication 4 · 105 ·dm [mm] 0.75 ... 1.0 · n* Grease 1 · 104 ·dm [mm] 1.0 · n* Oil lubrication* For the limit speed, please refer to the bearing parameter table dm u003d (d +D)/2. These values u200bu200bare used as reference values u200bu200bfor bearings with the temperature difference between the inner and outer rings ΔT 5K. When the temperature difference between the inner and outer rings is greater (electric spindle bearings), please consult Schaeffler. 8: Rotation speed n of cylindrical roller bearing. The elevation distance is approximately 13 to 19 times the radial expansion (factor F). The smoothness of the surface, the elastic expansion of the inner ring and the contraction of the shaft will all affect the F value. Please refer to Table 13 to determine the coefficient F value. Lifting distance A u003d F · ΔGdB u003d hollow shaft inner diameter d’ u003d shaft diameter in the middle of the tapered shaft dB/d’ u003d hollow shaft diameter ratio ΔG u003d radial clearance variation. Example: Cylindrical roller bearing should have zero clearance after installation. First, install the outer ring into the bearing seat. Then, put the shaft with the inner ring into the bearing housing, and rotate it slowly to avoid scratches on the main shaft. Move the inner ring until the radial clearance reaches 20 μm, and then slowly rotate the spindle. The clearance measurement is carried out by moving the inner ring radially, such as raising the main shaft, and fixing the indicator near the bearing at the same time. Elevation distance A u003d factor F · Radial clearance change ΔG, example dB/d’ u003d 0.55, radial clearance change ΔG u003d 20 μm Raise distance A u003d 17 · 20 μm u003d 340 μm u003d 0.34 mm. Measure the axial distance between the inner ring and the adjacent shaft shoulder. For example, use a gauge block to measure 4 points with a difference of 9 points. Grind the spacer ring according to the measured value and install it against the shaft shoulder. Finally, install the bearing and check whether it is zero clearance. When installing cylindrical roller bearings, as long as the inner ring is not tilted relative to the outer ring and the spindle rotates slowly during installation, there will be no scratches. It is best to simplify the installation process by heating the bearing housing and outer ring. The installation method described above can ensure that the clearance meets the requirements after installation, and the position of the inner ring will not change due to vibration during rotation.